CONTROVERSIES IN ORTHODONTICS
INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
Contents
Introduction Origin of controversies Etiology Of Malocclusion a] Genetic V/s environmental factors. b] Role of nasal obstruction and tongue thrust Extraction vs Non Extraction One phase vs. two phase Third molars a dilemma! Or is it? Orthopedics in orthodontics : fiction or reality Occlusion, orthodontic treatment and TMD www.indiandentalacademy.com
Introduction
Controversy – a prolonged argument/ dispute especially when conducted publicly. Orthodontics – the art of straightening teeth The science performed in ortho Without a clear formulation of the hypothesis to be tested Without any evaluation of the validity and reproducibility of the variables chosen for study
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Introduction
ď Ž ď Ž
Dev. is based on clinical experience and induction based on single cases. Field of ortho is broad
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The background, nature, and origins of orthodontic controversies Orthodontics
traditionally has been a speciality in which opinions of leaders were important Angle Begg Tweed
“Disagreements are then a risk rather than exception”
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So where does the problem arise?
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Variety of opinion – “Good Orthodontics” No consensus exist today, and some opinions are even mutually exclusive.
0ne phase vs. two phase treat.
The techniques are based upon subjective assessment of quality rather than any scientific validation “opinion – based” / “evidence based” Such science can neither validate the superiority of a technique nor help to make rational choices among alternatives
Bimax case – begg tech/ SWA www.indiandentalacademy.com
Orthodontic research
Number of observed general rules, and causal relationships Repeated observation confirmed explanation of a general set of rules
E.g. Angle’s Class II elastic force
Deductive research “A hypothesis based upon present experience is formulated and an experiment is carried out to test this generally” Karl Popper in 1968
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Patient’s assumptions concerning the ability of health professionals:
Distinguish b/w normal & abnormal
Accurately characterize abnormalities by a process of differential diagnosis
Assess the severity of the condition and judge the consequences of intervention vs. non intervention
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Patient’s assumptions concerning the ability of health professionals:
Identify alternative clinical procedures and know the relative odds in favor of desired outcome for each option
Evaluate the relative cost/ risk/ benefit ratios of each alternative
Make a decision that is comprehensible to the patient & best meets the patient’s need
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Controversies of growth prediction
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Controversies of growth prediction
ď Ž
Why would an orthodontist place importance on being able to predict?
ď Ž
Can orthodontist predict craniofacial development at therapeutically useful levels of accuracy and precision?
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Controversies of growth prediction
Why would an orthodontist place importance on being able to predict? To understand and modify the general process of development To control our patients response to therapeutic inclination E.g. Max. intrusion splint – restrict max. growth
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Controversies of growth prediction
Can orthodontist predict craniofacial development at therapeutically useful levels of accuracy and precision? Different craniofacial phenomenon are predictable with different levels of precision. Orthodontist should examine their degree of success for each parameters. restrict max. growth – Class II restrict mand. growth – Class III
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Orthodontists can predict…………….
The head and face of pre- adolescent and adolescent children will continue to change in shape and size until the age of 20 yrs.
The growth of jaws and face from mixed dentition period to maturity will be greater in inferior direction than in anterior.
Class II malocclusion identified after eruption of molars to occlusal contact will rarely, if ever resolve spontaneously.
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Orthodontists can predict…………….
Antr. crowding & rotations visible after the permanent incisors have completely erupted will only rarely resolve spontaneously.
In absence of adjacent tooth, permanent teeth would tend to migrate mesially.
Unopposed teeth would tend to supraerupt.
The prominence of dentition within the face will decrease during maturation.
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Orthodontists can predict…………….
Therapeutic intervention that alter occlusal intercuspation will tend to open Mb plane angle.
Mb incisors that have been displaced or proclined antrly during treat. will tend to relapse in the post retention period.
Arches in which buccal segments have been expanded will tend to relapse to their pre treat. widths. Esp Mb arches. (Mx arches corrected before fusion of midpalatal suture can be excepted from this rule) www.indiandentalacademy.com
Orthodontists can predict…………….
Intercanine width that has been increased returns to their pre treat. widths.
Attempts to retract canine by anchoring them posterior teeth tend to result in advancement of posterior teeth esp. in Mx arches.
Angle of Mb would tend to be close with respect to cranium spontaneously from mixed dentition period to maturity in the absence of treat. www.indiandentalacademy.com
Orthodontists cannot predict…………….
The magnitude and timing of spontaneous growth remodelling at specific sites in head, face and jaws. (e.g. Mb Growth)
The impact of specific therapeutic intervention upon the expression of each individual inherent growth potential. (e.g. functional therapy)
Amount of correction that can be achieved at a specific anatomic loci. www.indiandentalacademy.com
Orthodontists cannot predict…………….
The amount of post therapeutic accommodation/ relapse that can occur. (e.g. orthagnathic surgeries)
Completeness of particular patients: co-operation with the therapeutic process.
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Etiology of malocclusion Genetic vs. environmental Role of nasal obstruction & tongue thrust 1.
2.
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Genetic vs. environmental
Hapsburg jaw – Prognathic jaw Inherited two possible ways: Inherited disproportion between the size of teeth and that of the jawsproducing crowding/spacing. Inherited disproportion between size/shape of upper and lower jaws – producing improper occlusal relations.
anthropological evidence - population groups that are genetically homogenous Melanesians of Philippine islands
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Genetic vs. environmental
mobilization of population increase in malocclusion in modern man. Edward Angle and his contemporaries - improper function of jaws earlier part of the 20th century - Mendelian genetics Prof. Stockhard (1930) Increase in malocclusion accompanying urbanization is the result of increased out-breeding
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Genetic vs. environmental
Hypothesis was cast in doubt since Dogs – carry gene of achondroplasia Chung et al- on Polynesian population of Hawaii Migration inter-racial breeding malocclusion There was no evidence of dramatic facial deformities as observed in Stockhard’s experiments.
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Genetic vs. environmental
Familial and Twin studies - Lundstrom (1984), Corrucini (1980), Potter (1986), Bolton and Brush, Harris and Johnson (1991)
No single explanation for malocclusion.
Result of a complex interplay of function, heredity or environment.
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Genetic vs. environmental
Hereditary abnormalities in relation to malocclusion can be classified as: A) Dental characteristics B) Dental malocclusions C) Skeletal malocclusions D) Malformation syndromes
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Genetic vs. environmental
A) Dental characteristics
Tooth size- Osborne et al (1958) - twin studies tooth crown dimensions are strongly determined by heredity.
Supernumerary teeth- Brook (1984) and Rule (1995) supernumerary teeth follow a familial trait, but they do not follow a simple Mendelian pattern. Jasmine’s (1993) work on twins also supports this.
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Genetic vs. environmental
Shape – Alversalo and Portin (1969) missing and malformed lateral incisors common gene effect. Their association with familial trends, other dental anomalies like missing teeth, ectopic canines, etc. suggests a polygenic etiology. Significant genetic components : Etiology of submerged primary molars (Kurol-1981) Ectopic maxillary canines (Zilberman-1990) and (Peck1994). www.indiandentalacademy.com
Genetic vs. environmental
Tooth morphogenesis – Amelogenesis imperfecta Dentinogenesis imperfecta Hypodontia Ectodermal dysplasia
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Genetic vs. environmental
B) Dental malocclusion
Harris and Smith (1982) crowding, rotations and occlusal relations are entirely nongenetic in nature. If seen in Siblings - intra familial environment bone based direction and proportions - moderately strong genetic corelation. variables of tooth positions are environmentally induced.
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Genetic vs. environmental
Lundstrom, Chung: on sibling pairs showed that the genetic component over jet > overbite > molar relationship C) Skeletal malocclusions 1] Sagittal a) Class.11 Div1: Twin studies indicate the presence of high familial correlation, showing polygenic inheritance.
b) Class.11 Div 2: syndrome than a malocclusion. Studies by Markovich, Kloeppel, Korkhous, and Peck et al - genetics plays a vital role in its etiology.
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Genetic vs. environmental
c) Class.III: most heavily influenced malocclusion by genetics. Suzuki (1961) - 1362 class-III individuals Results - increased incidence in members of the same family. 2] Vertical Anterior open bite - Blacks Deep bite - Whites “All these indicate a genetic difference in the inherent facial morphology.” www.indiandentalacademy.com
Genetic vs. environmental
D) Malformation syndromes
1] Mandibular Deficiency a) Robin Complex: Etiology-Heterogeneous. b) Treacher Collins Syndrome: Autosomal dominant c) Stickler Syndrome: Autosomal dominant
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Genetic vs. environmental
2] Mandibular Prognathism a) Macrocephaly: Autosomal dominant. b) Klinefelter’s Syndrome: xxy- Karyotype. c) Marfan’s Syndrome: Autosomal dominant 3] Facial Asymmetries a) Hemifacial-Microsomia: Sporadic, with autosomal dominant or récessive nature.
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Genetic vs. environmental
Proffit
“The pertinent question for the etiologic process of malocclusions not whether there are inherited influences on the jaws and teeth, because obviously there are, but whether malocclusion is often caused by inherited characteristics”
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Role of nasal obstruction & tongue thrust
Respiratory pattern as an etiologic factor for malocclusions: Respiration - Primary determinant of jaw and tongue posture. Altered respiratory pattern change posture of head, jaw, and tongue alters equilibrium jaw growth and tooth position affected.
Effects - Increased face height, supra-erupted posteriors, open bite, mandible rotates downward and backward & a narrow maxillary arch. www.indiandentalacademy.com
Role of nasal obstruction & tongue thrust Harvold, Tomer and Vargevik (81): Total nasal obstruction in monkeys, for a prolonged time malocclusion. Placing a block on the roof of the mouth, forcing the tongue to a more downward position variety of malocclusion.
Because total nasal obstruction in humans is so rare: whether partial nasal-obstruction is a risk factor in causing malocclusion?
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Role of nasal obstruction & tongue thrust
Primates do not have same naso respiratory mechanism as humans. Total nasal obstruction not seen in humans. Type of malocclusion is determined by individual animal’s pattern of adaptation.
Does nasal obstruction equates mouth breathing + lip-apart posture.
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Role of nasal obstruction & tongue thrust
Ballard and Gwynne-Evans (1958)
Lip incompetence not necessarily associated with mouth breathing. Nose breathers, who have a lip - apart posture, usually have post seal with tongue against soft palate as an adaptive mechanism.
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Role of nasal obstruction & tongue thrust
Contemporary view: 2 opposing principles, leaving large gray area between them: Total nasal obstruction is highly likely to alter pattern of growth and lead to malocclusion & individuals with high percentage of oral respiratory is over-represented in longface population. Majority of individuals with long-face deformity have no evidence of nasal obstruction because some other etiological factor as principal cause. www.indiandentalacademy.com
Role of nasal obstruction & tongue thrust
Tongue-thrust as etiologic factor: Profitt (72) –the term tongue-thrust is a misnomer, since it implies that the tongue is forcefully thrust forward. Laboratory studies Forces is less in tongue thrust than with normal Swallowing - controlled physiologically - hence cannot be considered a habit. Cannot blame tongue-thrust as a cause for open bite useful physiologic adaptation, if you have an open bite
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Role of nasal obstruction & tongue thrust
Individual with an open bite also has a tongue-trust swallow. The reverse is not true. Role of tongue in etiology of malocclusion??? “Equilibrium theory” : Light but sustained pressure by tongue against the teeth A typical swallow is < 1 seconds. swallows 800 times in a day, while awake Total/ day is < 1000 times, & thus 1000 seconds of pressure has little/no effect.
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Role of nasal obstruction & tongue thrust
Current view point: Tongue –thrust is primarily seen in 2 circumstances: In young children with normal occlusion – transitional stage in normal physiologic maturation. In individuals of any age with displaced anterior teeth – adaptive. Hence it is more a “Result” than a “cause” However tongue posture and size is more important.
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Role of nasal obstruction & tongue thrust
Light continuous pressure for more duration change in tooth position.
Spacing – large & forwardly placed tongue Crowding – small tongue
If posture is normal, tongue-thrust swallow has no clinical significance.
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Dr. Ashish Singh
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Studies related to nasal obstruction & malooclusion
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Studies related to nasal obstruction & malooclusion
Research leads to 2 opposing principles: Total nasal obstruction – highly likely to alter the pattern of growth & lead to malocclusion. Majority of individuals with long face pattern of deformity have no evidence of nasal obstruction & must have some other etiological factor as the principle cause.
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Studies showing direct correlation between pattern of respiration and malocclusion
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Experimental Studies Of Respiratory Obstruction: a.
James Mc Namara-
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caused complete nasal obstruction in primates using silicon plugs.
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Found downward & backward rotation of mandible & increased lower facial height.
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Experimental Studies Of Respiratory Obstruction b. Harvold
Miller – Classical studies in young rhesus monkey. Latex plugs inserted into the nasal passages – forcing to breathe through the mouth. Gradual adaptation from nasal to oral respiration. Some animals positioned mandibles downward & backward. Some, rhythmically lowered and raised the mandibles. Some positioned the mandible downward & forward.
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Experimental Studies Of Respiratory Obstruction i.
Soft tissue changes occurred first â&#x20AC;&#x201C; notching of upper lip & grooving of the tongue.
i.
Moderate skeletal changes in animals who lowered mandible for each breath.
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Experimental Studies Of Respiratory Obstruction iii.
Dramatic changes
In mandibular morphology –at the gonial region and chin in animals which maintained lowered mandibular posture.
Distance from nasion to chin increased- lowering of mandible.
Distance from nasion to hard palate increased –downward displacement of maxilla.
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Clinical Studies Of Respiratory Obstruction
Linder – Aronson & Backstrom compared facial types & type of occlusion in nose breathers and mouth breathers. Found : Greater nasal resistance – children with long narrow faces & high narrow palate. No direct correlation between mouth breathing & type of occlusion - particularly overbite / jet.
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Studies which conclude that Individuals with long face pattern of deformity have no evidence of nasal obstruction
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Studies which conclude that Individuals with long face pattern of deformity have no evidence of nasal obstruction
Bushey-Compared lateral cephalograms –pre and post surgically.
Found no relationship between linear measurements of the adenoids and nasal respiration.
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Studies which are not univocal about the results
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Studies which are not univocal about the results Fields et alcompared respiratory modes of normal and long-faced subjects using respirometer. ď&#x192;&#x2DC;
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1/3rd of the long-faced individuals have less than 50% nasal respiration and none of the normal-faced individuals have such low values. Most of the long faced individuals are predominantly nasal breathers.
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Studies which are not univocal about the results Clinical study by James A. McNamara Jr. â&#x20AC;&#x201C; Preliminary analysis of skeletal & dental characteristics of 40 patients. ď&#x192;&#x2DC;
Results indicate craniofacial relationships with mouth breathing are variable & associated with number of facial patterns.
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Controversies in Functional Appliances
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Changing trends of Class II treatment
Early treatment methods: Late 1800s – head gear Early 1900s – Angle era Use of head gear abandoned Same result with Class II elastics Also Kingsley Antr. Inclined plane – “jumping the bite” Mode of correction of both was supposed to promote Mblar growth.
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Changing trends of Class II treatment
Advent of ceph:
Both Class II elastics / antr. Bite plane Correction mainly by forward movement of lower arch
Head gear – more of skeletal effect (Weislander) Head gear – again mainstay of Class II treatment in USA. Overlook the forward movement of lower arch – results were unstable www.indiandentalacademy.com
Changing trends of Class II treatment
In Europe Removable functional appliance Early app.: Monobloc of Pierre Robins (1907) – not very popular Andressen’s activator – loose fitting retainer Correction of Class II by forward Mblar growth. Andressen associated with Haupl – “ Functional Jaw Orthopedics” Very popular in Europe in mid 20th century – largely unaccepted in USA
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Changing trends of Class II treatment
1970 – 1980s - popular in USA Graber , Woodside, Mc Namara, Harvold etc. Use of head gear & functional app. in orthodontics sparked 3 main controversy: Which is superior???? Are they effective???? Are they needed????( early vs. late treatment)
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Changing trends of Class II treatment
Which is superior???? Proffit and Tulloch – RCTs 1998 UNC AJO - DO Comparison of effect of head gear / bionator or activator with controls Results: Both are useful HG – Max. Restriction Func. Appl – Mb growth Some didn’t show good result – unfavorable growth pattern
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Changing trends of Class II treatment
Which is superior????
Univ of Pennsylvania (Ghafari) 1998 AJO - DO Comparison Head Gear and Functional Regulator Found no difference in effect. Both appl. are equally effective.
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Changing trends of Class II treatment
Which is superior????
Univ of Florida RCTs 1998 AJO - DO Keeling, Wheeler et al. Bionator / HG & bite plate Both appl. are effective.
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Changing trends of Class II treatment
Which is superior???? Class II correction in patients treated with Class II elastics and with fixed functional appliances : a comparative study. Birgitta Nelson et al AJO – DO 2000 Quantitative evaluation of skeletal & dental changes Both type of changes were seen with both app.. More skeletal with Herbst treated group.
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Changing trends of Class II treatment
Are they effective????
Do func app. & Head Gear work?
Long term studies of HG – very effective in shorter duration Melson – during treat. with cervical pull HG Maxilla grew downward and backward 8 years post treat follow up – Maxilla resumed its forward growth
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Changing trends of Class II treatment
Melson 2003 Head gear – restricting growth of maxilla distalizing 1st molar Follow up – on removal Mx. continued to grow downward & forward 1st molar returned to normal position Similar finding – Derringer After discontinuing HG – Mx. continued to grow downward & forward
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Changing trends of Class II treatment
Studies of functional appliances:
Short term results of various appliances
Activator , Herbst, activator with HG, Herbst with HG
Esp Herbst with HG (Der mout & Aelbos)
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Changing trends of Class II treatment
Studies of functional appliances:
Long term results – all the effect by the functional appl seemed to be lost over the long term.
Pancherz (1981) Europ J ortho– although Herbst appliance resulted in good growth of Mb during treat period. Long term – no difference b/w grp treated with Herbst appliance & untreated controls.
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Changing trends of Class II treatment
De Vincenzo (1998)
Acceleration of growth - functional app. Reduction in rate of growth after functional app. therapy So that after 3 -4years it was increasingly difficult to distinguish b/w 2 groups
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Changing trends of Class II treatment
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Changing trends of Class II treatment
Studies of Frankel app.: Mc Namara popularized FR-2 There was increase in growth – retrospective study Almeida et al AJO – DO (2002) Increase of about only 1.1mm after wearing FR-2 for 17 months
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Changing trends of Class II treatment
Studies of Twin Block: Retrospective studies of Lund et al Correction of Class II by proclination of lower incisors Uprighting of upper incisors Review of literature of Chun – Meta Analysis No advantage of functional app. on long term
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Changing trends of Class II treatment
Studies that indicate functional appl can result in growth:
Rabie et al 2003 AJO-DO
Growth of condyle & glenoid fossa
Findings are:
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Changing trends of Class II treatment
The expression of Sox 9 and type II collagen are accelerated and enhanced when the mandible is positioned forward.
The amount of new bone formation during mandibular advancement and after the removal of bite-jumping
No significant difference in new bone formation could be found after the appliance was removed when compared with natural growth
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Changing trends of Class II treatment
Functional appliance therapy accelerates and enhances condylar growth by accelerating the differentiation of mesenchymal cells into chondrocytesmore cartilage matrix.
This enhancement of growth did not result in a subsequent pattern of subnormal growth for most of the growth period;
This indicates that functional appliance therapy can truly enhance condylar growth.
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Changing trends of Class II treatment
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Changing trends of Class II treatment ď Ž
Mills CM, Mc Culloch KJ (2000) reported the long-term treatment effects of Twin Block appliance:
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To ascertain if any residual increase in the mandibular length remained at the end of the follow-up period, that is, three years after phase I Twin Block treatment.
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Changing trends of Class II treatment ď Ž
However, there was a slight reduction in the mandibular growth (0.7 mm) after treatment.
ď Ž
Much of the significant increase in the mandibular length achieved during the active phase of the treatment with the Twin Block appliance was still present 3 years later when the subjects had matured into the permanent dentition phase.
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Changing trends of Class II treatment
Are functional appliance needed? Early vs. late treatment RCTs of Univ. of North Carolina Tulloch, Phillips, Proffit Compared pts treated in 2 phases. 1st phase – functional app. / head gear 2nd phase – fixed app. Controls – only fixed app. therapy
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Changing trends of Class II treatment
Findings
No difference in need for extraction No diff. in need of complexity of orthog. surgery Difficulty of treatment with fixed appl. were similar Same no. of success & failures
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Changing trends of Class II treatment
No advantage of early treatment in:
Reducing treatment complexity Reducing need for extraction Reducing need for orthognathic surgery Reducing time of treatment with fixed appl.
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Changing trends of Class II treatment
Advantages of early treatment: Reduced risk of trauma to antr. Teeth Proved by – RCTs by Tulloch Better psychological development and self image Shown by – ‘O’ Brien et al.AJO-DO 2003
Proffit disagrees
“psychological development and self esteem occurs at adolescence, therefore early treatment before adolescence will have no advantage over late treatment with regards to psychological improvement”
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Changing trends of Class II treatment
RCT in Univ of Florida
Functional app. corrected malocclusion
But no diff b/w treated grp. & control grp. before starting phase II
Even when functional app. & HG were used part time as retainer – no advantage was seen.
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Changing trends of Class II treatment
Disadvantages of early treatment:
Increased cost of treatment Increased demand of patient cooperation Increased risk of iatrogenic tendency – caries root resorption e.g. Impacted canine – due to uprighting of lat. incisor
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Changing trends of Class II treatment
Controversies of timing of treatment in class II div1
i.
Intervention in pri dentition Early mixed dentition Mid mixed dentition( intertransitional period before the emergence of 1 st pm & perm. Mb. canine) Late mixed dentition (before the emergence of 2 nd pm & perm. Mx. canine) Anthony D. Viazis AJO-DO 1995 HG/ Func appl. – late mixed dentition
ii. iii. iv.
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Changing trends of Class II treatment
Prospective RCTs in Univ of Pennsylvania Ghafari in 1998
Treatment in late childhood was as effective as that in mid childhood
Timing of treatment in developing malocclusion may be optimal in late mixed dentition thus avoiding a retention phase before a later stage of ortho treat. with fixed appl.
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Resolution of functional appl. controversies The current rationale
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The current rationale
i. ii. iii. iv.
Taken from EDITORIAL of AJO-DO Jan 1998 Donald G. Woodside dentoalveolar changes restriction of forward growth of the midface stimulation of mandibular growth beyond that which would normally occur in growing children redirection of condylar growth from an upward and forward–directed growth to a posterior
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The current rationale v.
deflection of ramal form
v.
horizontal expression of mandibular growth from downward and forward to horizontal
v.
changes in neuromuscular anatomy and function that would induce bone remodeling
v.
adaptive changes in glenoid fossa location to a more anterior and vertical position. www.indiandentalacademy.com
The current rationale
Validity of research is sometimes questionable???
Problems with ceph studies:
Too small sample SNA, SNB Angle – change with incisors position Landmarks are difficult to locate Condyle is often positioned antrly. Radiographic images are often obscured by other cranial structure Small amount of statistical significance – may not clinically signi.
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The current rationale
Problems of Histologic Studies: Voudoris (1998), Angelopoulos (1991) Increased activity of bone by using tritiated thymidine increase in Mb length Only reflect increased metabolic activity. Individual variation occurs in the TMJ. Anatomical variation in sections.
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The current rationale
Miscellaneous problems: Patient cooperation. Anatomic physiologic difference b/w animal models & human subjects. Age variation – juveniles are compared with adolescents or young adults. Difficulty in finding untreated controls, so results are often compared with untreated normal subjects.
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Variation in appliance design – act dissimilar ways Variation in appliance action – Amount of Mblar advancement Type of construction bite Prescribed time of wear Duration of treatment varies Homogeneity in sex, age, and control b/w study groups is lacking
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“Truth itself is often concealed in such a way that the harder you look for it, the harder it is to find.” Singer’s Yentl
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Dr. Ashish Singh
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Extraction vs. Non- Extraction
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Extraction vs. Non- Extraction i. ii.
“To extract or not to extract” 2 main reasons for extraction Space – crowding Allow teeth to move – skeletal Class II / Class III camouflaged. History Late 1800’s – early 1920’s From 1930’s – 1970’s Between 1970’s – 1990’s www.indiandentalacademy.com
Extraction vs. Non- Extraction
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Extraction vs. Non- Extraction
Late 1800 – early 1920’s Late 1800 saw a casual attitude towards extraction 1902 Edward H. Angle Facial esthetics/ stability of results Rousseau – perfectibility of man Wolff – biologic concept “Wolff's law of bone” “Bone trabeculae were arranged in response to stress lines on the bone”
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Extraction vs. Non- Extraction
Angle propose 2 key concepts Skeletal growth influenced readily by external forces Proper function of dentition would be the key for maintaining teeth in their correct position Proper occlusion favorable force direction bone growth increase stability Bodily movement of teeth Edgewise Appl. – “Bone growing appl.”
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Extraction vs. Non- Extraction
Relapse: Adequate occlusion not reached “If correct occlusion is produced result is stable, if results not stable it was the fault of the orthodontist & not the theory.” Dentofacial esthetics: Devoted much time in search of ideal facial form Prof. Wuerpel – “tremendous variety in human faces makes it impossible to specify any one facial form as the ideal.” www.indiandentalacademy.com
Extraction vs. Non- Extraction
Ideal facial esthetics teeth are in ideal occlusion arch expansion is necessary Angle’s Dogma: Alignment of teeth - Expansion of dental arches Use of elastics – bring teeth into occlusion Extraction was not necessary for stability & esthetics Calvin Case – argued that neither stability nor esthetics would be satisfactory in the long term for many patients after alignment from expansion.
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Extraction vs. Non- Extraction
Controversy culminated in a widely publicized debate: Dewey and Case in the dental literature of 1920s. Angle’s follower won – extraction disappeared b/w World War I & II. South Americans – did not agree with Angle’s appl sys. Removable (Crozat) or partially banded appl. ( twin wire) were used accepted non extraction philosophy.
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Extraction vs. Non- Extraction
From 1930 – 1970’s Charles Tweed re – treated with extraction Extraction was reintroduced by the late 1940’s Raymond Begg – Begg appl. Further strengthened by Prof. Stockard’s – breeding exp.
Malocclusion could be inherited Genetically determined disparities b/w tooth size & jaw size Lack of proximal wear – modern man www.indiandentalacademy.com
Extraction vs. Non- Extraction
Between 1970 – 1990’s – revival of non extraction
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Extraction vs. Non- Extraction
Why the decline in extraction rates more recently? Premolar extraction does not guarantee stability of tooth alignment. Little, Wallen and Riedel – 1981 AJO. MC Reynolds and Little – 1991 Angle Orthod. Argument “If result not stable either way, why sacrifice teeth at all”. v/s. “If extraction cases are unstable, non-extraction would be worse”. www.indiandentalacademy.com
Extraction vs. Non- Extraction
Changing views of esthetics – fuller and more prominent lips, than the orthodontic standards of 1950s & 1960s.
Change from fully banded to largely bonded appliances made it easier to expand arches – border line case generally treated better without extraction.
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Extraction vs. Non- Extraction
Both Tweed’s and Begg’s rational for extraction, lost some of their validity. The contemporary Perspective: Majority of patients can be treated without extraction, but by no means all. Extraction can be undertaken to compensate for: Crowding. Incisor protrusion. Camouflage skeletal discrepancies For surgery
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Extraction vs. Non- Extraction (The contemporary Perspective)
Treatment modalities converting borderline cases into non – extraction cases: Early intervention:
Use of ‘E’ space. Proximal stripping of primary teeth. Space regainers with space maintainers. Arch expansion. Use of functional appliances. Molar distalization. Bonded attachments rather than banded ones.
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Extraction vs. Non- Extraction (The contemporary Perspective)
Treatment modalities converting borderline cases into non –extraction cases: Adults: Molar distalization. Inter-proximal reduction. Arch expansion. Surgery for skeletal discrepancies.
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Extraction vs. Non- Extraction (The contemporary Perspective)
Recommendations for expansion V/S extraction: Esthetic considerations: Expansion makes teeth more prominent Extraction makes teeth less prominent Facial esthetics – unacceptable on either too-protrusive or too-retrusive. Acceptable range of protrusion and biologic limitations – expand Control space closure - extraction www.indiandentalacademy.com
Extraction vs. Non- Extraction (The contemporary Perspective)
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Extraction vs. Non- Extraction (The contemporary Perspective)
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Extraction vs. Non- Extraction (The contemporary Perspective)
Size of the nose and chin – relative lip prominence Large nose and/ or a large chin: Non extraction – move incisor forward ( but doesn’t diminish the labiomental sulcus too much). Extraction – controlled space closure Lack of well defined mentolabial sulcus/ lip strain: Increase lower facial height/ protrusion of antrs Extraction is choice www.indiandentalacademy.com
Extraction vs. Non- Extraction (The contemporary Perspective)
Thin lips Proclining incisors fuller lips & more vermilion show – more attractive Retraction in thin lips – aged face appearance
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Extraction vs. Non- Extraction (The contemporary Perspective)
Poorly defined mentolabial sulcus
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Extraction vs. Non- Extraction (The contemporary Perspective)
Incisor position determine the extraction /non- extraction decision
No esthetic liability: Extraction space – less retraction Non- Extraction – w/o protruding incisors
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Extraction vs. Non- Extraction (The contemporary Perspective)
Stability consideration:
How much can arches be expanded?? Lower arch Upper arch
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Extraction vs. Non- Extraction (The contemporary Perspective) Lower arch: More constrained than upper – limited expansion Lower incisor 2mm Lip pressure limiting factor in forward mov. of lower antrs. Lingually tipped lower incisors – can be moved further forward than upright lower antrs. Expansion transverse > anteroposterior (except in canine area) Canine – relatively high lip pressure Pre molar & molar – relatively low cheek pressure
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Extraction vs. Non- Extraction (The contemporary Perspective)
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Extraction vs. Non- Extraction (The contemporary Perspective)
Upper arch expansion:
Opening mid palatal suture Sutural expansion – 50 % skeletal & 50 % dental Limiting factors - Cheeks pressure 12 mm total expansion - Buccal cortical bone – fenestration (> 3mm)
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Extraction vs. Non- Extraction (The contemporary Perspective)
Summary For Class I crowding / protrusion: < 4mm of arch length discrepancy with no vertical discrepancy: non-extraction.
Arch length discrepancy – 5-9mm Non-extraction – transverse expansion of premolar segment. Extraction – any pattern depending on hard and soft tissues.
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Extraction vs. Non- Extraction (The contemporary Perspective)
> 10mm : of arch length discrepancy
Extract
1st choice – all 1st pre molars or Upper 1st pre molars & lower lat. Incisors Rarely - all 2nd pre molars or all 1st molars
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Extraction vs. Non- Extraction
Indications for extraction of 1st premolars (Tweed and Begg): Maximum anterior retraction and camouflage of Class II div I. Maximum anchorage – Less taxing of anchorage. Eruptive sequence – space for canines. Space discrepancy > 10mm for Class I M.O. – crowding. Class I bimax cases
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Extraction vs. Non- Extraction
When the term "orthodontic extraction" arises, the tooth that immediately comes to mind is the first premolar.
(1) it usually erupts before any of the other posterior teeth with the exception of the first permanent molar;
(2) its extraction allows eruption of the permanent canine; and (3) it is in the center of each half of the arch and therefore the space provided by its extraction can alleviate anterior and/or posterior crowding.
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Extraction vs. Non- Extraction
Indications for 2nd premolar extraction: Nance, Carey, Dewey and Thompson (Begg) Good profile and mild crowding. Straight profile and moderate crowding. Class II div. 1 dental on Class I skeletal with mild mandibular crowding. Case of maxillary set back surgery. Crowded and out of arch. Correction of molar relation.
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Extraction vs. Non- Extraction
Indications for Incisor extraction: Lower Incisor
Severely crowded mandibular arch – Reidel – increased stability – 1940 Jacobson – extracted mandibular incisors.
Severe
protrusion. Periodontal breakdown /periapical lesion. Severely fractured. Bolton discrepancy.
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Extraction vs. Non- Extraction
Reidel extraction of mandibular incisors decreases treatment time – 2 laterals instead of 2 premolars Kokich and Shapiro – 4 successfully treated cases with single mandibular incisor extraction. Maxillary central incisors: Caries. Fracture. Dilacerated. Badly impacted.
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Extraction vs. Non- Extraction
Maxillary lateral incisor:
a. Crowding in incisor region with mesial displacement of root apices of canines - Gardiner.
Indications for 1st molar extractions (Wilkinson):
Carious / endo treated/ multifilled. Esthetic considerations with properly developed 2nd and 3rd molars – large nose and chin – pre molars dished face. Open bite cases? Supraerupted teeth. Crowding in premolar region and incisors in good relation.
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Extraction vs. Non- Extraction
Indications for canine extractions: (Creekmore):
Periodontally involved. Horizontally impacted – tooth movement? Distally tipped/ severely rotated / grossly displaced buccally/palatally.
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Extraction vs. Non- Extraction
controversy within the extraction of second molars
Liddle (AJO 1977) believes that many malocclusions develop because of the eruption forces of the permanent second molars and that extracting premolars is treating the "effects" rather than the "cause" of the malocclusion.
Samir E. Bishara and Paul S. Burkey, AJO-DO 1986 May
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Extraction vs. Non- Extraction
Samir E. Bishara and Paul S. Burkey, AJO-DO 1986 May
Facilitation of treatment using removable appliances Reduction in the amount and duration of appliance therapy Disimpaction of third molars Faster eruption of third molars Prevention of "late" incisor imbrication Facilitation of first molar distal movement
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Extraction vs. Non- Extraction
Distal movement of the dentition only as needed to correct the overjet Prevention of "dished-in'' appearance of the face at the end of facial growth Fewer "residual" spaces at the end of orthodontic treatment Less likelihood of relapse Good functional occlusion Good mandibular arch form Reduction in incisal overbite
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Extraction vs. Non- Extraction
Indications for 2nd molar extraction: Chipman AJO 1961 Mild –moderate arch length discrepancy with good esthetics. Distalization of first molar. Relieve lower incisor crowding. Relieve impaction of 2nd premolar. Severely carious / ectopically erupted / rotated.
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Extraction vs. Non- Extraction (The contemporary Perspective)
Present understanding
Non extraction treat.: Fuller profile & less stability Extraction treat.: Flattening of profile & more stability
Decision is based upon: Soft tissue profile Growth – size of nose & chin increases, lips – flatter & thin www.indiandentalacademy.com
Extraction vs. Non- Extraction (The contemporary Perspective)
Borderline cases – non extraction
Imp. Consideration
Lip separation – increases with tooth prominence. Thick, full lips – can afford prominent incisors. Cephalometric readings can serve as guidelines. Nasolabial angle Lip incompetence Size of nose & chin
Johnston – with extraction – about 2 mm flatter
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Extraction vs. Non- Extraction
Drobocky and Smith: AJO-DO 1989 March Soft-tissue profiles were examined in 160 orthodontic patients treated with removal of four first premolars. Records of 10- to 30-year-old patients were selected at random from five sources: Tweed foundation Kesling Rocke group From 2 practioners – PEA Pre molars enucleated at an early age
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Extraction vs. Non- Extraction Results : extraction of four first premolars generally did not result in a "dished-in" profile. Approximately 10% to 15% of cases could be defined as excessively flat alter treatment 80 % - 90% of patients treated by extraction of four first premolars had soft-tissue measurements that suggested the profile was improved by treatment or remained satisfactory throughout treatment.
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Extraction vs. Non- Extraction
Paquette, Beattie, and Johnston - AJO-DO 1992 Jul Borderline extraction and nonextraction comparison
63 patients with Class II, Division 1 malocclusions – 33 extracn & 30 non extracn
Data provide little support for the claims that premolar
extraction — as opposed to expansion and bite-jumping — must flatten the profile enough to ruin the face.
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Extraction vs. Non- Extraction
Faruk Ayhan et al Angle Orthod 2003 “Effects of extraction & non extraction treatment on Class I & Class II subjects”
Successfully treated cases, whether by extraction or non extraction, same soft and hard tissue profile were seen.
Extraction means a more retrusive profile or dished – in profile seems to be unacceptable. www.indiandentalacademy.com
Extraction vs. Non- Extraction
Faruk Ayhan et al Angle Orthod 2004 Influence of extraction treatment on Holdway Soft – tissue Measurements
Generalization concerning the negative effects of extraction of four 1st pre molars on the profile are not true.
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Dr. Ashish Singh
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THIRD MOLARS:A DILEMMA! OR IS IT?
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The greatest enemy of truth is very often not the lie â&#x20AC;&#x201C; deliberate, contrived, and dishonest, but the myth â&#x20AC;&#x201C; persistent, persuasive and unrealistic. John F. Kennedy Yale Univ. June 11, 1962
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THIRD MOLARS:A DILEMMA! OR IS IT?
The present controversy In 1859, Robinson wrote “the dens sapientiae is frequently the immediate cause of irregularity of the teeth”.
In a survey of more than 600 orthodontists and 700 oral surgeons
Laskin found, that 65% were of the opinion that third molars sometimes produce crowding of the mandibular anterior teeth.
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THIRD MOLARS:A DILEMMA! OR IS IT?
Removal versus the preservation of third molars
Third molars should be removed even on a prophylactic basis, because they are frequently associated with future orthodontic and periodontal complications as well as other pathologic conditions.
There is no scientific evidence of a cause and effect relationship between the presence of third molars and orthodontic and periodontal problems.
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THIRD MOLARS:A DILEMMA! OR IS IT?
What is the relationship b/w 3rd molars & lower incisor crowding?
Are 3rd molars impaction predictable?
Is there rationale on how to handle 3rd molars at the end of ortho Tx ?
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THIRD MOLARS:A DILEMMA! OR IS IT?
Relationship between 3rd molars and incisor crowding: The changes in Lower incisor that occur with time in both untreated and orthodontic treatment populations. Untreated normal: Bishara et al (1989AJO and 1996 AO): Evaluated changes in lower incisor between 12 and 25 years and again at 45 years – findings indicated :
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THIRD MOLARS:A DILEMMA! OR IS IT?
Increase in tooth size arch length discrepancy with age – consistent decrease in arch length. Average changes 2.7mm in males; 3.5mm in females. Similar findings by Lundstrom (1968) Sinclair and Little (1983 AJO):
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THIRD MOLARS:A DILEMMA! OR IS IT?
Orthodontically treated patients:
Fastlicht (1970 AJO) found that in orthodontically treated subject- 11% had 3rd molars, but 86% had crowding.
Little et al (1981AJO) observed that 90% of extraction cases that were well treated orthodontically ended up with an unacceptable lower incisor crowding.
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THIRD MOLARS:A DILEMMA! OR IS IT?
ď Ž
Long term studies :
ď Ž
Incidence as well as the severity of mandibular incisor crowding increased during adolescents and adulthood in both the normal untreated individuals as well as orthodontic treated patients, after all retention is discontinued.
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THIRD MOLARS:A DILEMMA! OR IS IT?
Bramante (1990) observed that many clinicians consider some form of indefinite retention to avoid crowding in later stages of maturation.
Studies relating 3rd molar to crowding of dentition
Studies indicating lack of correlation between mandibular 3rd molar and post retention crowding Retrospective / prospective studies
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Studies relating 3rd molar to crowding of dentition:
Two studies which are most widely quoted Bergstrom and Jensen (1961) Vego (1962 AO) Bergstrom and Jensen (1961) To determine the extent to which 3rd molars are responsible for secondary tooth crowding Cross-sectional study, 30 dental students - unilateral agenesis of upper 3rd molar 27 had agenesis of one lower 3rd molar.
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Studies relating 3rd molar to crowding of dentition:
On plaster cast they performed left-to-right comparisons of space conditions of both sides of each arch.
More crowding in the quadrant with 3rd molar present than in the quadrant with the third molar missing.
Mesial displacement of lateral dental segments on the side with 3rd molar present in the mandibular arch not in the maxillary arch.
The unilateral presence of a third molar did not have an effect on the midline.
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Studies relating 3rd molar to crowding of dentition:
Vego (1962 AO) Longitudinal study – 40 with 3rd molars and 25 with an congenitally missing 3rd molar. 2 time intervals – 1st :13 years- 2nd molar eruption; 2nd: average age of 19 years. All 65 cases – decrease in arch perimeter between the 2 intervals. But arch perimeter decrease was less noticeable in persons without lower 3rd molars.
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Studies relating 3rd molar to crowding of dentition: Schwarze (1975):
Compared a group of 56 patients with third molar germectomy to 49 subjects with third molars present.
significantly greater forward movement of first molars associated with increased lower arch crowding in the non extraction group.
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Studies relating 3rd molar to crowding of dentition: Lindquist and Thilander (1982)
Extracted third molar unilaterally in 52 patients
found more stable space conditions (less increase in crowding) on the extraction side compared with the control side in 70% of cases.
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Studies relating 3rd molar to crowding of dentition:
Belfast third molar study – Richardson M.E. (82-87). Produce further evidence “Pressure from behind” theory: Group of 51 subjects with intact lower arches and bilateral third molar present were examined at ages 13 and 18 years. On average these cases had an increase in lower arch crowding of slightly more than 1mm on each side during the 5 year observation period. In some quadrants the crowding increased by as much as 4mm and only 16% of quadrants demonstrated no change in crowding.
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Studies relating 3rd molar to crowding of dentition:
The cause of this kind of crowding is controversial and often confused with the causes of post treatment relapse, which may be quite different.
Whether this pressure results from: Dev. 3rd molar. Physiologic mesial movement / drift. Anterior component of force derived from forces of occlusion on mesially inclined teeth.
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Studies relating 3rd molar to crowding of dentition:
Another school of thought is (Graber, Woodside, SelmerOlsen):
“In absence of 3rd molar, the dentition has room to settle distally under anterior pressures caused by late growth or soft tissue changes”.
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Studies indicating lack of correlation between mandibular 3rd molar and post retention crowding:
A] Retrospective studies: Kaplan (1974AJO): investigated whether mandibular third molars have a significant influence on post treatment changes in the mandibular arch, specifically on anterior crowding relapse. 75 orthodontically treated patients – pre and, post treatment and 10 years post treatment study models and lateral ceph 3 groups
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Studies indicating lack of correlation between mandibular 3rd molar and post retention crowding:
1st group - 30 persons with both third molars erupted to the occlusal plane, in good alignment buccolingually, and of normal size and form.
2nd group - 20 persons with bilaterally impacted third molars. All were candidates for surgical removal of the third molars on the basis of postretention periapical radiographs.
3rd group - 25 patients with bilateral agenesis of the mandibular third molars.
Presence of 3rd molar does not produce a greater degree of lower anterior crowding or rotational relapse after cessation of retention.
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Studies indicating lack of correlation between mandibular 3rd molar and post retention crowding:
Ades et al (1990AJO-DO), in a cephalometric study on a similar sample found :
No significant differences in mandibular growth patterns between various 3rd molar groups – erupted, impacted or agenesis.
Majority of cases have incisal crowding, but no correlation with 3rd molars.
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Studies indicating lack of correlation between mandibular 3rd molar and post retention crowding:
Lifshitz (1982)
evaluated the effect of lower premolar extraction versus non extraction as well as the presence of absence of lower third molars, on mandibular incisor crowding.
In all groups evaluated, there is a significant decrease in arch length and a significant increase in crowding.
But there were no significant difference between the groups that did or did not have premolar extractions or whether third molars were present or missing. www.indiandentalacademy.com
Studies indicating lack of correlation between mandibular 3rd molar and post retention crowding:
B] Prospective studies: Lindquist and Thilander (1982AJO): To determine the effect of the prophylactic removal of mandibular third molars on lower incisors. 3rd molar on one side were extracted at an average of 15.5 years and the other side left as a control. Study casts and cephl on these patients 3 years postoperatively. Unable to predict which patients benefit from prophylactic extraction – both side similar changes
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Studies indicating lack of correlation between mandibular 3rd molar and post retention crowding:
Southhard (1991AJO-DO) et al
Measured proximal contact tightness between the mandibular teeth in cases with bilaterally unerupted third molars. The measurements were taken before and after the unilateral removal of one third molar.
Surgical removal of 3rd molar – no significant effect on contact tightness.
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Studies indicating lack of correlation between mandibular 3rd molar and post retention crowding:
Pirttiniemi et al (1994) evaluated the effect of removal of impacted third molars on 24 individuals at 3rd decade of life Dental casts were evaluated before & 1 year after extraction. Extraction of 3rd molar allowed for slight distal drift of 2nd molar but no significant change in incisal area. Summary : 3rd molars do not play a significant, i.e., quantifiable, role in mand. antr. crowding.
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Third Molar Impactions:
Clinical problem in managing adolescent ortho patients.
Are there any morphologic factors hat may affect the eruption or impaction of 3rd molars?
Should we enucleate 3rd molars at an early age if we think they will be impacted?
How predictable is the ultimate 3rd molar position, from earlier observations of its inclination?
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Morphologic factors that can influence space available for 3rd molar:
Bjork et al (1956):
examined 243 cases to estimate the relationship between various cephalometric parameters and the space available for mandibular third molars.
Identified three skeletal factors that may influence third molar impaction:
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Morphologic factors that can influence space available for 3rd molar:
Vertical direction of condylar growth as indicated by mandibular base – ramus angle (Gonial angle).
Decreased mandibular length – Cd-Pog.
Backward – directed eruption of mandibular dentition as determined by degree of alveolar inclination.
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Morphologic factors that can influence space available for 3rd molar:
Capelli (1991 AO) 60patients of four 1st premolar extraction Findings of pre & post Tx. Ceph suggested 3rd molar impactions – predominant vertical Mb growth Other indicators: A long ascending ramus Short Mb length Greater mesial crown inclinations of 3rd molars
Summary – some morphologic factors that are related to greater incidence of 3rd molar impaction.
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Enucleation of 3rd molars & their prophylactic extractions
Bjork et al (1956) found 20-25% risk of impaction of third molars in Scandinavian males. Dachi and Howell (1961) – found similar ratio in U.S. Dichotomy b/w proponents & opponents of extraction Opponents of extraction the risk of complications during surgery. there are three major areas of economic concern in the third molar extraction:
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Enucleation of 3rd molars & their prophylactic extractions i.
Can the cost of the â&#x20AC;&#x153;routineâ&#x20AC;? removal of third molars as a preventive procedure be justified for the 80% who will not have impacted third molars?
ii.
What are the added costs of such a procedure on the cost of health insurance?
iii.
What are the risks involved with the procedure and the use of GA? www.indiandentalacademy.com
Enucleation of 3rd molars & their prophylactic extractions
Proponents of the removal of third molars young adults between the ages of 18 and 22 years experience problems with their third molars
Anchorage preparation - distal movement of the first and second molars may be required.
Ricketts et al further indicated that removal of third molar buds at the age of 7 to 10 years is surprisingly simple and relatively atraumatic.
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Consensus Development Conferences On Removal Of 3rd Molars:
2 consensus – National Institution of Dental Research (1979) American Association of OMFS (1993). When and what condition – extraction of 3rd molar advised. 1. Lower incisor crowding – multifactorial etiology. If adequate room is available – every effort should be made to bring these teeth into functional occlusion.
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Consensus Development Conferences On Removal Of 3rd Molars:
Orthodontic treatment – distalization of molar ( tipping/ translation) – if causes impaction extract.
No evidence – 3rd molars needed for development of basal skeletal component of maxillary or mandibular.
Post-operative pain, swelling, infection etc. decreased if patients are young and roots 2/3rd developed.
If extraction is indicated – early extraction beneficial.
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Consensus Development Conferences On Removal Of 3rd Molars:
Enucleation at 7-9 years not acceptable – present predictive techniques not highly reliable
Inform patients about possible complications of extraction pain, swelling, trismus, nerve damage etc.
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Why are 3rd molars extracted
Lysell & Rhlin 1988 Records of 870 Swedish patients treated in 23 clinics in Sweden. Indication of 3rd molar removal: 27% - prophylactic, 25% - pericoronitis 14% - orthodontics, 25% - caries/pulpitis 3% - cysts, tumours etc. , 18%- other factors
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Conclusion
Incisor crowding is multifactorial – no evidence that 3rd molar is only or major etiologic factor
Only relationship – both occur approx same stage of dev. i.e. in adolescence & early adulthood
But this is not a cause and effect relationship
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Conclusion
The clinician has to have a justifiable reason to recommend the extraction of any tooth.
Has to consider the impact of the extraction decision on any future Tx plan from an orthodontic, periodontic, or prosthodontic aspect.
If extraction is indicated – remove in young adulthood rather than older age.
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REFERENCES
Proffit “Contemporary orthodontics” 3rd ed. Birte Melson “Current controversies in orthodontics” Samir E. Bishara “Third molars: A dilemma! Or is it?” AJO-DO 1999; 115: 628-33. Margaret E. Richardson “The role of the third molars in the cause of late lower arch crowding: A review.” AJO-DO 1989; 95 : 79-83. Faruk Ahyan – The influence of extraction treatment on Holdway soft-tissue measurements AO – 2004; 74: 167173
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REFERENCES
Faruk Ahyan – Effects of extraction and non extraction treatment on Class I and Class II subjects AO – 2003; 73: 3642. Donald G. Woodside – Do functional appliances have an orthopedic effect? AJO-DO Jan 1988. Aelbers & Dermaut - Orthopedics in orthodontics: Part I, fiction or reality – a review of the literature AJO-DO 1996 110: 513-9 Aelbers & Dermaut - Orthopedics in orthodontics: Part II, fiction or reality – a review of the literature AJO-DO 1996 110: 667-71
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REFERENCES
Gianelly – One phase versus two phase treatment AJO-DO 1995 vol 108 No 5 Camilla Tulloch – Outcome in a 2-phase randomized clinical trial of early Class II treatment AJO-DO 2004;125:657-67 Robert M. Ricketts – A statement regarding early treatment AJO-DO Vol 117 No.5 Birgitta Nelson – Class II correction in patients treated with Class II elastics and with fixed functional appliances: A comparative study AJO-DO 2000;118:142-9
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REFERENCES
Anthony D. Viazis – Efficient orthodontic treatment timing AJO-DO 1995;108:560-1
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Extraction vs. Non- Extraction (The contemporary Perspective)
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I canâ&#x20AC;&#x2122;t believe, so many types!!!
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Well, it looks alien
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I think, it is edible !
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Dad says his is optical
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food pattern s
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I â&#x20AC;&#x2DC;ll get a bag
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Thank you !!
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Dad thinks heâ&#x20AC;&#x2122;s big Brain!!
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Son,cheese roll looks good!!!
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I would like to leave you with an inspirational saying
“Coming together is a beginning Keeping together is progress Growing together is success”.
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